Prior to the present invention, "wood biscuit joining" has been relatively recently introduced to professional and home workshops. The technique involves gluing an elliptical or similarly shaped wafer of wood or cellulose material into slot-type holes generally of a semicircular shape cut into the two wooden parts to be joined. The wafer is not merely glued but caused to swell inside the slots, forming an extremely high strength bond virtually invisible from outside.
Such wafers or biscuits are readily available in various sizes. Special rotary blades are also available for cutting the holes or slots; these of course must be used in power tools which accept them. Typically, the biscuit blades in use have a generally hexagonal shape, may be from about three to about five inches in diameter, for example, and have clearing teeth as well as cutting teeth. The special power tools which accept the blades are designed to be hand-held, which is the source of the problem.
Difficulties in using the hand-held biscuit slot cutter include its unwieldy shape and weight, problems in coordinating the position, direction and depth of the cut, steadying, and even locating the correct position for the slot. The slots on the two pieces of wood to be joined must be correctly placed because the placement of the biscuit may affect the accuracy of the joint; likewise the direction and angle of the slot must coordinate with both pieces of wood.
The present invention provides a fixed mount for the biscuit blade, thus eliminating many of the problems of accuracy and the requirements of vigilant balance and hand-eye coordination.
Radial arm saws have long been known, and mechanisms for adjusting the height, for example of radial arm saws, such as disclosed by Rosenthal in U.S. Pat. No. 3,565,136 are also known in the art. Rosenthal provides a pivot for the frame which holds the radial arm saw on the saw arm. Other attachments for radial arm saws in the prior art include means for clamping the wood specimen for a particular type of cut, such as, in the case of Kimber, U.S. Pat. No. 3,466,025, making a wedge cut. Also known in the prior art are various types of adjustable or movable guards for the blade, which may be typified by Kumasaka et al, in U.S. Pat. No. 4,799,416. We are not aware, however, of an attachment to a radial arm saw for the specific purpose of employing a biscuit slot cutter.